Re: [PATCH 3/3] gdbserver: xtensa: add call0 support

[Max Filippov <jcmvbkbc at gmail dot com>]

On Mon, Feb 13, 2017 at 10:43 AM, Luis Machado
<lgustavo@codesourcery.com> wrote:
> On 01/18/2017 05:50 PM, Max Filippov wrote:
>>
>> Correctly handle a0- registers on requests from remote gdb. This fixes
>>
>>   'Register 1 is not available'
>>
>> and subsequent assertion in the remote gdb connecting to the gdbserver:
>>
>>   'findvar.c:291: internal-error: value_of_register_lazy:
>>     Assertion `frame_id_p(get_frame_id (frame))' failed.'
>>
>> The register structure is the same for windowed and call0 ABIs because
>> currently linux kernel internally requires windowed registers, so they
>> are always present.
>>
>> 2017-01-18  Max Filippov  <jcmvbkbc@gmail.com>
>> gdb/gdbserver/
>
>
> Drop gdb/gdbserver/
>
>>         * linux-xtensa-low.c (C0_NREGS): New definition.
>>         (xtensa_fill_gregset): Call collect_register for all registers in
>>         a0_regnum..a0_regnum + C0_NREGS range.
>>         (xtensa_store_gregset): Call supply_register for all registers in
>>         a0_regnum..a0_regnum + C0_NREGS range.
>> ---
>>  gdb/gdbserver/linux-xtensa-low.c | 26 ++++++++++++++++++++++++++
>>  1 file changed, 26 insertions(+)
>>
>> diff --git a/gdb/gdbserver/linux-xtensa-low.c
>> b/gdb/gdbserver/linux-xtensa-low.c
>> index 98c0bf2..73fbfe2 100644
>> --- a/gdb/gdbserver/linux-xtensa-low.c
>> +++ b/gdb/gdbserver/linux-xtensa-low.c
>> @@ -39,12 +39,15 @@ enum regnum {
>>         R_A0 = 64
>>  };
>>
>> +#define C0_NREGS 16
>> +
>
>
> This is duplicating code from gdb/xtensa-linux-nat. Common nat code could be
> added to gdb/nat/ in an xtensa-specific file.

Ok.

>>  static void
>>  xtensa_fill_gregset (struct regcache *regcache, void *buf)
>>  {
>>    elf_greg_t* rset = (elf_greg_t*)buf;
>>    const struct target_desc *tdesc = regcache->tdesc;
>>    int ar0_regnum;
>> +  int a0_regnum;
>>    char *ptr;
>>    int i;
>>
>> @@ -72,6 +75,17 @@ xtensa_fill_gregset (struct regcache *regcache, void
>> *buf)
>>    collect_register_by_name (regcache, "ps", (char*)&rset[R_PS]);
>>    collect_register_by_name (regcache, "windowbase", (char*)&rset[R_WB]);
>>    collect_register_by_name (regcache, "windowstart", (char*)&rset[R_WS]);
>> +
>> +  a0_regnum = find_regno (tdesc, "a0");
>> +  ptr = (char *)&rset[R_A0 + 4 * rset[R_WB]];
>
>
> (char *) &rset... with space.
>
> More occurrences of this below.

Will fix.

>> +
>> +  for (i = a0_regnum; i < a0_regnum + C0_NREGS; i++)
>> +    {
>> +      if (4 * rset[R_WB] + i - a0_regnum == XCHAL_NUM_AREGS)
>
>
> This looks slightly error-prone. Adding parenthesis around the expression
> would look better and avoid compiler warnings.

Will add. It builds without warnings for me though.

>> +       ptr = (char *)&rset[R_A0];
>
>
> space issue mentioned above.

Will fix.

>> +      collect_register (regcache, i, ptr);
>> +      ptr += register_size (tdesc, i);
>> +    }
>>  }
>>
>>  static void
>> @@ -80,6 +94,7 @@ xtensa_store_gregset (struct regcache *regcache, const
>> void *buf)
>>    const elf_greg_t* rset = (const elf_greg_t*)buf;
>>    const struct target_desc *tdesc = regcache->tdesc;
>>    int ar0_regnum;
>> +  int a0_regnum;
>>    char *ptr;
>>    int i;
>>
>> @@ -94,6 +109,17 @@ xtensa_store_gregset (struct regcache *regcache, const
>> void *buf)
>>        ptr += register_size (tdesc, i);
>>      }
>>
>> +  a0_regnum = find_regno (tdesc, "a0");
>> +  ptr = (char *)&rset[R_A0 + (4 * rset[R_WB]) % XCHAL_NUM_AREGS];
>> +
>
>
> space issue.

Will fix.

>> +  for (i = a0_regnum; i < a0_regnum + C0_NREGS; i++)
>> +    {
>> +      if (4 * rset[R_WB] + i - a0_regnum == XCHAL_NUM_AREGS)
>
>
> parenthesis around the expression.

Will add.

-- 
Thanks.
-- Max